In the 1920s, the USPS placed giant concrete arrows every ten miles across the United States to guide pilots along the first transcontinental air mail routes. Hundreds still exist (though they've lost their bright yellow paint and night beacons). LOVE. And MUST FIND. Airmail Pilots, Mail Route, 1920S Airmail, Giant Airmail Arrows, Concrete Arrows, Giant Concrete, Yellow Arrows, Air Mail, Bright Yellow
by Ken Jennings
Every so often, a hiker or a backpacker will run across something puzzling: a ginormous concrete arrow, as much as seventy feet in length, just sitting in the middle of scrub-covered America. What are these giant arrows? Jeopardy champ Ken Jennings solves the mystery.